“It does have an impact both on the infrastructure and on railcars,” Metro spokesman Dan Stessel said. “On the infrastructure side because metal contracts in cold weather and expands in heat, over time that expansion and contraction of the rails can lead to cracks or broken rails that often manifest themselves on days like today.”

Staying Safe in the Cold

Things appeared to be running smoothly Wednesday evening, but the chilly weather Wednesday morning caused a cracked rail near the Naylor Road station, leading to single-tracking and delays on the Green Line.

Cracked rails are not uncommon when the temperatures drop, Metro said, especially on its above ground portions of track, and there's no way to avoid them.

In a lot of ways, the physics of a cracked rail can’t be stopped, Stessel said.

“The bottom line is: Every railroad in America that has seasons deals with cracked rails at some point,” he said.

Metro, which had 28 cracked rails last year, regularly checks the rails.

Metro wasn’t the only transit agency with trouble Wednesday. Amtrak said a one inch section of track along the Northeast Corridor near Princeton Junction, N.J., cracked, but trains kept moving through the area on other tracks.